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Imitrex: Uses, Dosage, Side Effects & Warnings
Patients with coronary artery disease who are receiving SYNTHROID should be closely monitored for cardiac arrhythmias during surgical procedures. There are certain populations where we pay closer attention to thyroid medication dosing. Another group is those that have underlying cardiac disease or are at risk for atrial fibrillation. And a third is those that have severe, long-standing hypothyroidism. Overtreatment or undertreatment with levothyroxine may have negative effects on different systems throughout the human body.
What is levothyroxine?
Carefully monitor glycemic control, especially when thyroid therapy is started, changed, or discontinued see Warnings and Precautions (5.5). Thyroid hormone increases metabolic clearance of glucocorticoids. Initiation of thyroid hormone therapy prior to initiating glucocorticoid therapy may precipitate an acute adrenal crisis in patients with adrenal insufficiency.
Avoid driving or hazardous activity until you know how this medicine will affect you. You may receive your first dose in a hospital or clinic setting to quickly treat any serious side effects. Biochemical assessment incorporated measurement of serum TSH, T3, and T4. TSH lower limit of quantification was 0.2 mIU/L and upper limit of normal was 5.6 mIU/L, as indicated by the shaded area. Some key points that I discuss with the patients during appointments are, one, is that this is an open conversation.
- Biotin supplementation is known to interfere with thyroid hormone immunoassays that are based on a biotin and streptavidin interaction, which may result in erroneous thyroid hormone test results.
- Thyroid hormones do not readily cross the placental barrier see Use in Specific Populations (8.1).
- I talk about the fact that it’s important to take the medication in the same timing and pattern each day, take it on an empty stomach minutes before they eat.
- Do not stop using any medications without first talking to your doctor.
- Be sure your doctor knows if you also take stimulant medicine, opioid medicine, herbal products, or medicine for depression, mental illness, Parkinson’s disease, serious infections, or prevention of nausea and vomiting.
- Reduce the SYNTHROID dosage or discontinue temporarily if signs or symptoms of overdosage occur.
ADVERSE REACTIONS
- Usually it should be taken at least 30 to 60 minutes before eating breakfast, or at bedtime (3 or more hours after the evening meal).
- In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively.
- You need an earlier test if you’re not feeling well, if you start or stop taking any other medications that can influence the TSH level, if you get pregnant, or plan pregnancy.
- Do not take more than 200 milligrams of oral Imitrex within 24 hours.
- There are safety considerations as SYNTHROID should not be used for treatment of obesity or for weight loss.
Published studies report that levothyroxine is present in human milk following the administration of oral levothyroxine. No adverse effects on the breastfed infant have been reported and there is no information on the effects of levothyroxine on milk production. Adequate levothyroxine treatment during lactation may normalize milk production in hypothyroid lactating mothers with low milk supply. Addition of levothyroxine therapy in patients with diabetes mellitus may worsen glycemic control and result in increased antidiabetic agent or insulin requirements. Carefully monitor glycemic control after starting, changing, or discontinuing SYNTHROID see Drug Interactions (7.2).
It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor. In adult patients with primary hypothyroidism, monitor serum TSH levels after an interval of 6 to 8 weeks after any change in dosage. In patients on a stable and appropriate replacement dosage, evaluate clinical and biochemical response every 6 to 12 months and whenever there is a change in the patient’s clinical status. The recommended starting daily dosage of SYNTHROID in pediatric patients with primary, secondary, or tertiary hypothyroidism is based on body weight and changes with age as described in Table 2.
- With hypothyroidism, you will need to take thyroid replacement such as levothyroxine for the rest of your life.
- Administer SYNTHROID as a single daily dose, on an empty stomach, one-half to one hour before breakfast.
- Seizures have been reported rarely with the institution of levothyroxine therapy.
- You should take your medication every day on an empty stomach, preferably 0.5h-1h before breakfast (alternatively, you can take the dose at bedtime, at least 3 hours after the last meal).
- Long-term carcinogenicity studies in animals to evaluate the carcinogenic potential of levothyroxine have not been performed.
Titrate the dosage (every 2 weeks) as needed based on serum TSH or free-T4 until the patient is euthyroid see Dosage and Administration (2.2). Myxedema coma is a life-threatening emergency characterized by poor circulation and hypometabolism and may result in unpredictable absorption of levothyroxine sodium from the gastrointestinal tract. Use of oral thyroid hormone drug products is not recommended to treat myxedema coma.
Call your doctor if your symptoms do not improve, or if you have more than 4 headaches in one month (30 days). Use the drop-down menu below to select your state and see the specific language required to prevent generic substitution. When prescribing SYNTHROID, protecting your script can ensure your patients receive SYNTHROID every time they refill their prescription. That’s because substitutions can be made at the pharmacy if the prescription is not properly protected with the Dispense as Written (DAW) state-specific language.
Patient resources
Using the levothyroxine dosage calculator is simple and intuitive. It will help you determine the drug’s right dose and give a hint of where to start and where to aim. Be sure your doctor knows if you also take stimulant medicine, opioid medicine, herbal products, or medicine for depression, mental illness, Parkinson’s disease, serious infections, or prevention of nausea and vomiting. These medicines may interact with sumatriptan and cause a serious condition called serotonin syndrome.
HYPOTHYROIDISM MEDICATION1,2*
Monitor for cardiac arrhythmias during surgical procedures in patients with coronary artery disease receiving suppressive SYNTHROID therapy. Monitor patients receiving concomitant SYNTHROID and sympathomimetic agents for signs and symptoms of coronary insufficiency. The recommended daily dosage of SYNTHROID in pregnant patients is described in Table 3.
Concurrent use of tyrosine-kinase inhibitors such as synthroid npo imatinib may cause hypothyroidism. Monitor serum free-T4 levels and maintain in the upper half of the normal range in these patients. Do not administer in foods that decrease absorption of SYNTHROID, such as soybean-based infant formula see Drug Interactions (7.9). Whether treated or not, subclinical hypothyroidism is a yellow flag that should put a patient on a ‘regular thyroid laboratory tests’ list. Remember to test TSH not earlier than 6-8 weeks after treatment initiation or levothyroxine dosage change. The pituitary gland controls the thyroid gland by the TSH — thyroid-stimulating hormone, which stimulates the thyroid to produce hormones.
